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Reduced Doses of PCV-7 May Reduce Nasopharyngeal Carriage of Pneumococcus in Infants

Posted Jul 31 2009 11:40am
Laurie Barclay, MD

July 15, 2009 — Infants who receive 2 or 3 primary doses of 7-valent pneumococcal conjugate vaccine (PCV-7) have a decreased rate of nasopharyngeal carriage of pneumococcus vs infants who are not vaccinated, according to the results of a randomized controlled trial reported in the July 8 issue of the Journal of the American Medical Association.

"The effects of reduced-dose schedules of...PCV-7 on pneumococcal carriage in children are largely unknown, although highly relevant in the context of subsequent herd effects," write Elske J.M. van Gils, MD, from Wilhelmina Children's Hospital, University Medical Center Utrecht in Utrecht, the Netherlands, and colleagues.

The goal of this study was to determine the effects of a 2-dose and 2 plus 1-dose PCV-7 schedule on nasopharyngeal pneumococcal carriage in infants vs those who did not receive the vaccine.

Between July 7, 2005, and February 14, 2008, in a general community in the Netherlands, 1003 healthy newborns, each with one of their parents, were enrolled, randomly selected to 1 of 3 groups, and followed up to age 24 months. The 3 study groups were 2 doses of PCV-7 at 2 and 4 months; 2 plus 1 doses of PCV-7 at 2, 4, and 11 months; or no dosage (control group). The primary endpoint of the study was rates of vaccine serotype pneumococcal carriage in infants in the second year of life.

After both PCV-7 schedules, vaccine serotype pneumococcal carriage was significantly decreased at 12 months. In the 2-dose and 2 plus 1-dose schedule groups, vaccine serotype pneumococcal carriage rates were 25% and 20%, respectively, vs 38% in the control group (both P < .001).

In the 2 plus 1-dose schedule group, vaccine serotype pneumococcal carriage had decreased further at 18 months to 16% and to 14% at 24 months both P < .001. In the 2-dose schedule group, however, vaccine serotype pneumococcal carriage was stable at 18 months 24%; but decreased further to 15% at 24 months. Vaccine serotype pneumococcal carriage in the control group remained approximately 36% to 38% until 24 months.

"The reduction of pneumococcal carriage obviously reduces the number of cases of invasive pneumococcal disease," said Fernando Artiles-Campelo, MD, a microbiologist in molecular epidemiology at Dr. Negrín University Hospital, Las Palmas de Gran Canaria, Canary Islands, Spain, told Medscape Pediatrics. "The fact that reduction occurs in both vaccination schedules is important in order to design a possible universal vaccination, because the total number of doses would be reduced if we use the 2-doses schedule."

JAMA. 2009;302:159-167.


note: PCV7 is not used in childhood vaccination in Malaysia
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